FTPClient getSystem method call returns null value on VMS systems.
This command is successfully processed by server, and its response was "200 VMS
OpenVMS 7.2 ......".
getSystem method is waiting only for "215" (SYSTEM_NAME) response, but "200" is
an other right response (COMMAND_OK).
real world where all things are not as they should be so I just changed the
code to accept a positive completion (any 2xx response). That should fix
the problem without breaking anything for anyone else.